Martin J. O’Fallon’s 1938 donation of 860 acres was one of the last major additions to the Denver Mountain Park system. This donation connected Corwina Park on the creek with Pence Park to the south. Together the three parks comprise 1,487 acres of contiguous parcels. Most of the park acreage is open space that protects and sustains the Bear Creek corridor including wetlands, riparian forest, open meadows, watershed, and evergreen forests.
O’Fallon is a favored spot for family picnics along bear Creek. Consequently it fills up quickly especially weekends during the summer months. O’Fallon Mountain Park has an extensive system of trails. It is possible to hike east to Corwina Park or west to Pence Park. O’Fallon also provides access to the Bear Creek Trail. All trails in O’Fallon are closed to mountain bikes and hiker only except the Bear Creek Trail which traverses the park from Corwina Park to Pence Park. There is no mountain bike access to the Bear Creek Trail from the O’Fallon Park trailheads.
Picnicking and restroom facilities are available in the central portion of the park with nearby parking.
The old Bear Road which is closed to motorized traffic provides a short hike to an iconic stone fireplace (missing its roof) visible along Bear Creek and which commemorates Mr. O’Fallon’s donation. O’Fallon is also a favorite spot for fishing along Bear Creek.